If both your cranks rock sideways together, attatched to the bottom bracket axle, then it is the axle which is lose. This will casue all kinds of strange noises. You need to tighten the bottom bracket or if it is a cartridge, get it replaced.
If the cranks rock independantly, then they are lose and will quickly damage the square hole at the centre if not tightened.
Regarding your wheel bearings, spin the wheel by hand. Lose bearings are easy to feel by a side-to-side rocking. Tight bearings will catch and grind. If these are cup and cone style they are fairly easy to adjust. I cant say how if they are industrial cartridge bearings. Some people confuse a sealed cup and cone bearing (ie having some rubber seal) with a sealed cartridge bearing.
Dont confuse the wheel bearings with the freewheel bearings, the cogs of the freewheel make lots of ratchet noises but their bearings are not load-bearing.
If you really dont know, then try and find a decent bike shop to sort out the problem.